Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 212025 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 425 PM EDT Sun May 21 2017 .SHORT TERM...
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(This evening through Monday night) Issued at 425 PM EDT SUN MAY 21 2017 19z sfc analysis shows a cold front approaching central Kentucky with new convection developing along it and east into the Cumberland Valley. Far eastern Kentucky is still seeing light showers tracking north out of southwestern Virginia. Even on satellite, the clouds are more cumuliform over the western parts of the CWA with breaks opening up. These should help to send temperatures up into the middle to upper 70s in those locations allowing for more instability to full the development of thunderstorms. Will continue the mention of heavy rain potential in the HWO as the PWs remain high and we have a few spots of low FFG due to the storms of the past couple of days. Currently, temperatures vary from the low 70s in the northeast where the rain has been steadiest to the mid 70s elsewhere while dewpoints are generally in the mid to upper 60s. Winds have been mainly light and out of the south, but with some breaks for sunshine in the west they have picked up to between 10 to 15 mph from the southwest. The models are in better agreement aloft through the short term portion of the forecast as they all similarly depict the evolution of the nearby and rather large mid level trough. This low lies to the north of Kentucky tonight with nearly zonal flow across the state along with the passing of a relatively minor short wave by 12z Monday. Further amplification of the nearby pattern then takes place into Monday night as the western portion of the trough deepens over the Upper Midwest and starts to dig south with more energy setting up to pass through the southern Ohio Valley late in the period. Given the models` consistency and agreement have favored a blend with a lean toward the latest high resolution CAMS for details through the night. Sensible weather will feature another round of showers and storms for the forecast area before an eastward moving cold front shuts down activity toward midnight from west to east. High pressure follows briefly allowing the area to dry out through Monday evening before more moisture is lured up from the south and may return showers to the area by dawn Tuesday. Temperatures will be near normal through the period with highs in the mid 70s and lows in the mid 50s to lower 60s - though do anticipate a ridge to valley split developing in the lows for Tuesday morning - not so much tonight with the moisture and late CAA. Used the CONSShort and ShortBlend as the grids` starting point with some adjustments to lows Monday night owing to a ridge to valley split developing. As for PoPs, have tightened them up in the near term for radar and HRRR trends while also knocking them down into Monday night. .LONG TERM...(Tuesday through Sunday) Issued at 300 PM EDT SUN MAY 21 2017 The extended portion of the forecast begins on Tuesday with an amplified upper level pattern in place featuring strong ridging in the west with a longwave trough digging into the Midwest and into the OH Valley. This transitions to a more active and progressive pattern and less amplified through the coming week. The passing open low in the east swings through and into the New England states by Friday. The ridging mentioned in the west will slide east as well providing a break in the weather for Friday and Saturday, the last 2 days in the extended. The GFS and Euro show some disagreement on this solution but overall, there is agreement on at least Friday being dry. Closer to the surface, with broad closed low overhead and developing cold front over the southeast. In southerly flow, this will bring ample moisture northeast into the Appalachians and a good chance for showers and thunderstorms across the area. The upper low and remnant surface boundaries coupled with any leftover mesoscale boundaries will make for convection to initiate each day from Tuesday through Thursday. Maximum occurrence will be associated with the diurnal trend with cells peaking just after max heating and dissipating after sunset. The main threat will tend to remain heavy rain as instability and shear at this this point appear to be supportive of a strong storm or two at most. Thus will stick close to the Super Blend and may adjust dry according to the new Euro and neighbor consensus for Day 6 and 7.
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&& .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) ISSUED AT 225 PM EDT SUN MAY 21 2017 An approaching cold front will bring periods of showers, and perhaps a few thunderstorms to the area through the evening. Expect a gradual lowering in the ceilings and visibilities even outside of the storms, with most locations eventually seeing MVFR conditions overnight. Showers will gradually diminish from west to east tonight as the cold front passes through the area with MVFR ceilings scattering out from west to east through the end of the period. South to southwest winds around 5 kts will eventually shift to west northwest after the frontal passage. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...SHALLENBERGER AVIATION...GREIF is the U.S. government's official web portal to all federal, state and local government web resources and services.